The movie premiered today at the 73rd International Venice Film Festival.

The film tells the true story of Desmond Doss (played by Garfield), who enlists and is determined to save lives on the front line as a medic, but refuses to carry a gun on moral grounds.

The film derives its title from a battleground in Japan at the top of a towering cliff. US soldiers who climb its sheer face are met with bunkers and corpses, as well as Japanese bullets and flame-throwers.

During the brutal Battle of Okinawa, Doss single-handedly saved the lives of over 75 of his comrades. He was awarded the Medal of Honor by President Harry S Truman.

"The man who refuses to touch a weapon and wants to do something much higher than something as venal as killing in a war is a very high calling," Gibson said, adding that he did believe "just wars" exist.

This is the first movie Gibson has directed since “Apocalypto”, 10 years ago.

He said he felt like "a traffic cop" director while filming “Hacksaw Ridge”.

Garfield said Doss was much more inspiring than the web-weaving hero, whose Spandex costumes prompted Gibson’s jibe.

"The fact that this man, who is built as skinnily as I am, dragged men across the most rugged terrain under gun fire, sniper fire, the possibility of motors and shells, and then lowered them down a 75-foot escarpment... that’s like when you hear about mothers who lift trucks off babies," said the actor.

Garfield first came to international attention in 2010 with a supporting role in the film “The Social Network”.